ENERGY DEMAND HALVED, SELLING VALUE DOUBLED

Green building

The German district city of Mettmann is located near to the Rhine metropolis Düsseleldorf. In 1972 a 12,000 square metre apartment complex was constructed on a large park-like hillside plot. Two buildings of equal height, with staggered square green areas an characteristic balconies dominate its appearance. A full energetic refurbishment was completed in 2013.

ENERGY DEMAND HALVED, SELLING VALUE DOUBLED

Green building

The German district city of Mettmann is located near to the Rhine metropolis Düsseleldorf. In 1972 a 12,000 square metre apartment complex was constructed on a large park-like hillside plot. Two buildings of equal height, with staggered square green areas an characteristic balconies dominate its appearance. A full energetic refurbishment was completed in 2013.

The building complex is surrounded by high trees, and large areas of the original façade of cement-bound tiles, similar to concrete roofing tiles, were covered in moss. In consideration of the expected increase in value, the owners decided on the rear-ventilated clay brick curtain façade solution which was recommended by the architect Werner Kettler.

„In addition to the physical requirements which were prescribed for a state subsidy, the demands by the owners on the new building shell were also very high. As well as being dirt repellent, it was important to the decision-makers that this should have a long life, low susceptibility to scratches and impacts, a low risk of moss and dirt, good cleaning capability as well as a high quality appearance and sustainability“, reports architect Werner Kettler.

Before renovation

INDIVIDUALLY MANUFACTURED

Due to the different heights of the floors – the ground floor is one metre higher than the other floors – two different panel heights were required. The brick formats which are used are therefore not standard formats, but rather customised productions for the particular building.

The orange colour was modified at the individual wish of the architect. „After extensive consultations, we decided on an engobe surface. Because of the engobe, the surface is smoother and less porous; the selected orange colour appears somewhat warmer. The engobe surface repels dirt and the orange colour excellently matches the grey-bronze aluminium and silver-coloured balcony panels“, says architect Kettler.

The Mettmann apartment complex was refurbished according to an integrated energy concept. In addition to refurbishment of the shell of the building, most of the windows, flat roofs and cellar ceilings were renewed. In comparison with 2007 consumption of primary energy reduced from 370 kWh/(m²a) to 153.5 kWh/(m²a), and the final energy demand from 123 kWh/(m²a) to 54.0 kWh/(m²a), while CO2 emissions reduced from 84.2 kg/(m²a) to 40.5 kg/(m²a).

The refurbishment has therefore almost halved the values, emphasises architect Werner Kettler, and the increase in value for the owners can also be quantified. „Sales revenue has doubled!“